We will utilize the method of molecular dynamics simulations to study the free energy of binding of various endocrine-disrupting compounds to human and wildlife forms of the alpha isoform of the estrogen receptor (ERalpha) as a means of understanding how ERalpha is activated by EDCs. For this purpose we will simulate 100 different compounds, from several chemical categories, interacting with the ligand-binding domain (LBD) of ER. Our selection criteria for the 100 compounds will be based on the usage and origin of the compounds, the structural similarity and dissimilarity of the compounds, and the availability of relative binding affinity (RBA) data for each compound. To date our selection of compounds is consistent with a wide array of compounds encompassing: pollutants, plant products, steroids, and pharmaceuticals. The compounds we have chosen are all in the Endocrine Disrupter Knowledge Base (EDKB).